Synthesis and reactivity towards carbon monoxide of an optically active endo five-membered ortho-cyclopalladated imine: X-ray molecular structure of trans-(μ-Cl)2[Pd(κ-C,N-(R)-C6H4-CHN-CHMe-Ph)]2

(R)-1-Phenylethyl-benzylidene-amine (1) reacted with Pd(OAc)₂ in acetic acid at 60 °C under nitrogen affording the acetato-bridged dinuclear endo five-membered ortho-cyclopalladated compound (μ-OAc)₂[Pd(κ²-C,N-(R)-C₆H₄-CHN-CHMe-Ph)]₂ (2) in 65% yield. Compound 2 was converted by a metathesis reaction with LiCl into the corresponding chloro-bridged dinuclear cyclopalladated compound (μ-Cl)₂[Pd(κ²-C,N-(R)-C₆H₄-CHN-CHMe-Ph)]₂ (3). ¹H NMR of CDCl₃ solutions of compounds 2 and 3 treated separately with py-d₅, (R)-1-phenylethylamine and racemic 1-phenylethylamine were consistent with the endo cyclopalladated structure and the R absolute configuration of the chiral carbon atoms of compounds 2 and 3. Compounds 2 and 3 reacted with carbon monoxide in methanol affording, as major compounds, methyl 2-formylbenzoate (91% chemical yield) and the epimers of 3-methoxy-2-[(R)-1-phenylethyl]isoindolin-1-one (64% chemical yield) in ca. 20% diastereomeric excess, respectively. The trans isomer of compound 3 crystallized in the P2₁ monoclinic space group with a = 10.430(4) Å, b = 12.082(8) Å, c = 11.168(4) Å and β = 95.20(3)° and presented C-H?Cl intramolecular and C-H?Pd intermolecular non-conventional hydrogen bonds.     

Phase and rheological behavior of the polymerizable surfactant CTAVB and water

The phase and rheological behaviors of the polymerizable surfactant, cetyltrimethylammonium benzoate (CTAVB), and water as a function of surfactant concentration and temperature are investigated here. The critical micelle concentration (cmc) and the (cmc(2)), as well as the Krafft temperature (T(K)), are reported. A large highly viscous micellar solution region and hexagonal- and lamellar-phase regions were identified. The micellar solutions exhibit shear thickening in the dilute regime, below the overlapping or entanglement concentration. At higher concentrations, wormlike micelles form and the solutions show strong viscoelasticity and Maxwell behavior in the linear regime and shear banding flow in the nonlinear regime. The linear viscoelastic regime is analyzed with the Granek-Cates model, showing that the relaxation is controlled by the kinetics of reformation and scission of the micelles. The steady and unsteady responses in the nonlinear regime are compared with the predictions of the Bautista-Manero-Puig (BMP) model. Model predictions follow the experimental data closely.     

N,N-polymethylene-bisadenine complexes with d metal ions

The reaction of N⁹,N^9′-(tri or tetramethylene)-bisadenines (Ade₂C_x; x = 3 or 4) in HCl 2 M at 50 °C with MCl₂ · 2H₂O [M = Zn(II), Cd(II)] yields outer sphere compounds like the previously described [(H-Ade)₂C₃][ZnCl₄] · H₂O (3) and [(H-Ade)₂C₃]₂[Cd₂Cl₈(H₂O)₂] · 4H₂O (4) for Ade₂C₃ and the new {[(H-Ade)₂C₄][Cd₂Cl₆(H₂O)₂] · 2H₂O}_n (5) for Ade₂C₄. On the other hand, only in case of Zn(II) complexes by changing [HCl] to 0.1 M, the inner sphere compounds [H-(Ade)₂C₃(ZnCl₃)] (6) and [H-(Ade)₂C₄(ZnCl₃)] · 1.5H₂O (7) are obtained. X-ray diffraction study of compound 6, which represents the first inner sphere complex with a N⁹,N^9′-bisadenine, shows a zwitterionic form with one adenine ring protonated at N(1) while the other ring is coordinated via N(7) to a ZnCl₃ moiety as in other alkyl-adenine derivatives. In addition, with Ade₂C₄, is also possible to obtain another inner sphere complex: [(H-Ade)₂C₄(ZnCl₃)₂] · 3H₂O (8).     

A comparative study of the structures and reactivity of cyclometallated platinum compounds of N-benzylidenebenzylamines and cycloplatination of a primary amine

The reaction of cis-[PtCl(2)(dmso)2] with ligands 4-ClC(6)H(4)CHNCH(2)C(6)H(5) (1a) and 4-ClC(6)H(4)CHNCH(2)(4-ClC(6)H(4)) (1b) in the presence of sodium acetate and using either methanol or toluene as solvent produced the corresponding five-membered endo-metallacycles [PtCl{(4-ClC(6)H(3))CHNCH(2)C(6)H(5)}{SOMe(2)}] (2a) and [PtCl{(4-ClC(6)H(3))CHNCH(2)(4'-ClC(6)H(4))}{SOMe(2)}] (2b). An analogous reaction for ligands 2,6-Cl(2)C(6)H(3)CHNCH(2)C(6)H(5) (1c) and 2,6-Cl(2)C(6)H(3)CHNCH(2)(4-ClC(6)H(4)) (1d) produced five-membered exo-metallacycles [PtCl{(2,6-Cl(2)C(6)H(3))CHNCH(2)C(6)H(4)}{SOMe(2)}] (2c) and [PtCl{(2,6-Cl(2)C(6)H(3))CHNCH(2)(4'-ClC(6)H(3))}{SOMe(2)}] (2d) when the reaction was carried out in methanol and seven-membered endo-platinacycles [PtCl{(MeC(6)H(3))ClC(6)H(3)CHNCH(2)C(6)H(4)}{SOMe(2)}] (3c) and [PtCl{(MeC(6)H(3))ClC(6)H(3)CHNCH(2)(4'-ClC(6)H(3))}{SOMe(2)}] (3d) when toluene was used as a solvent. The reaction of 2,4,6-(CH(3))(3)C(6)H(2)CHNCH(2)(4-ClC(6)H(4)) (1e) produced in both solvents an exo-platinacycle [PtCl{(2,4,6-(CH(3))(3)C(6)H(2))CHNCH(2)(4'-ClC(6)H(3))}{SO(CH(3))(2)}] (2e). Cyclometallation of 4-chlorobenzylamine was also achieved to produce compound [PtCl{(4-ClC(6)H(3))CH(2)NH(2)}{SOMe(2)}] (2g). The reactions of endo- and exo-metallacycles with phosphines evidenced the higher lability of the Pt-N bond in exo-metallacycles while a comparative analysis of the crystal structures points out a certain degree of aromaticity in the endo-metallacycle.     

N,N-Dialkyl-2-iodoanilines: a versatile source for the synthesis of Pd(ii) complexes. Synthesis of novel OCP- and CCN-pincer palladium complexes

The reactivity of a series of N,N-dimethyl-2-iodoanilines bearing different chelating "arms" at the 3-position with Pd(2)(dba)(3) has been explored. 3-[(Diphenylphosphino)methyl]-2-iodo-N,N-dimethylaniline reacted with Pd(2)(dba)(3) and PPh(3) under aerobic conditions to give the OCP-pincer complex , which was formed by sequential C(sp(3))-H activation/oxidation at the alpha-position of the aniline N atom. On the other hand, under similar reaction conditions, 3-[2-(dimethylamino)ethyl]-2-iodo-N,N-dimethylaniline afforded the CCN-pincer complex , after a second C-H activation process at the formyl group of the initially formed OCN-pincer complex. In contrast, 2-iodo-3-(1H-1,2,4-triazol-1-ylmethyl)-N,N-dimethylaniline and 2-iodo-3-(pyrazol-1-ylmethyl)-N,N-dimethylaniline reacted with Pd(2)(dba)(3) and PPh(3), respectively, to give the 6-membered azapalladacycles and , in which the aniline nitrogen is merely a spectator substituent. Finally, treatment of iodide complex with Tl(TfO) afforded the CN-bidentate cationic complex. Solid-state structures of palladium complexes, and CH(2)Cl(2).3CH(3)OH.5H(2)O were determined by X-ray analysis.     

Surface versus volume effects in luminescent ceria nanocrystals synthesized by an oil-in-water microemulsion method

Pure and europium (Eu(3+)) doped cerium dioxide (CeO(2)) nanocrystals have been synthesized by a novel oil-in-water microemulsion reaction method under soft conditions. In-situ X-ray diffraction and RAMAN spectroscopy, high-resolution transmission electron microscopy, UV/Vis diffuse-reflectance and Fourier transform infrared spectroscopy as well as time-resolved photoluminescence spectroscopy were used to characterize the nanaocrystals. The as-synthesized powders are nanocrystalline and have a narrow size distribution centered on 3 nm and high surface area of ~250 m(2) g(-1). Only a small fraction of the europium ions substitutes for the bulk, cubic Ce(4+) sites in the europium-doped ceria nanocrystals. Upon calcination up to 1000 °C, a remarkable high surface area of ~120 m(2) g(-1) is preserved whereas an enrichment of the surface Ce(4+) relative to Ce(3+) ions and relative strong europium emission with a lifetime of ~1.8 ms and FWHM as narrow as 10 cm(-1) are measured. Under excitation into the UV and visible spectral range, the europium doped ceria nanocrystals display a variable emission spanning the orange-red wavelengths. The tunable emission is explained by the heterogeneous distribution of the europium dopants within the ceria nanocrystals coupled with the progressive diffusion of the europium ions from the surface to the inner ceria sites and the selective participation of the ceria host to the emission sensitization. Effects of the bulk-doping and impregnation with europium on the ceria host structure and optical properties are also discussed.     

EVALUATION OF TEXTILE DETERGENT EFFICIENCY OF MICROEMULSIONS IN SYSTEMS OF WATER NONIONIC SURFACTANT AND HYDROCARBON AT LOW TEMPERATURE

Washing efficiency of microemulsions in water/nonionic surfactant/hydrocarbon systems has been evaluated. Such microemulsions have proved to have an excellent performance as cleaning systems in conditions of minimum mechanical energy and at low temperatures. Their behaviour in the presence of small amounts of an ionic surfactant as well as the modifications promoted by the presence of builders have also been investigated.     

Relationships between Fe NMR, Mössbauer parameters, electrochemical properties and the structures of ferrocenylketimines

A comparative study of the electrochemical properties, ⁵⁷Fe NMR and Mössbauer spectroscopic data of compounds [(η⁵-C₅H₅)Fe{(η⁵-C₅H₄)-C(R¹)N-R²}] {R¹ = H, R² = CH₂-CH₂OH (1a), CH(Me)-CH₂OH (1b), CH₂C₆H₅ (1c), C₆H₄-2Me (1d), C₆H₄-2SMe (1e) or C₆H₄-2OH (1f) and R¹ = C₆H₅, R² = C₆H₄-2Me (2d)} is reported. The X-ray crystal structure of [(η⁵-C₅H₅)Fe{(η⁵-C₅H₄)-CHN-C₆H₄-2OH}] (1f) is also described. Density functional theoretical (DFT) studies of these systems have allowed us to examine the effects induced by the substituents of the “-C(R¹)N-R²” moiety or the aryl rings (in 1d-1f) upon the electronic environment of the iron(II) centre.     

Copper(II) hexaaza macrocyclic binuclear complexes obtained from the reaction of their copper(I) derivates and molecular dioxygen

Density functional theory (DFT) calculations have been carried out for a series of Cu(I) complexes bearing N-hexadentate macrocyclic dinucleating ligands and for their corresponding peroxo species (1c-8c) generated by their interaction with molecular O2. For complexes 1c-7c, it has been found that the side-on peroxodicopper(II) is the favored structure with regard to the bis(mu-oxo)dicopper(III). For those complexes, the singlet state has also been shown to be more stable than the triplet state. In the case of 8c, the most favored structure is the trans-1,2-peroxodicopper(II) because of the para substitution and the steric encumbrance produced by the methylation of the N atoms. Cu(II) complexes 4e, 5e, and 8e have been obtained by O2 oxidation of their corresponding Cu(I) complexes and structurally and magnetically characterized. X-ray single-crystal structures for those complexes have been solved, and they show three completely different types of Cu(II)2 structures: (a) For 4e, the Cu(II) centers are bridged by a phenolate group and an external hydroxide ligand. The phenolate group is generated from the evolution of 4c via intramolecular arene hydroxylation. (b) For 5e, the two Cu(II) centers are bridged by two hydroxide ligands. (c) For the 8e case, the Cu(II) centers are ligated to terminally bound hydroxide ligands, rare because of its tendency to bridge. The evolution of complexes 1c-8c toward their oxidized species has also been rationalized by DFT calculations based mainly on their structure and electrophilicity. The structural diversity of the oxidized species is also responsible for a variety of magnetic behavior: (a) strong antiferromagnetic (AF) coupling with J = -482.0 cm(-1) (g = 2.30; rho = 0.032; R = 5.6 x 10(-3)) for 4e; (b) AF coupling with J = -286.3 cm(-1) (g = 2.07; rho = 0.064; R = 2.6 x 10(-3)) for 5e; (c) an uncoupled Cu(II)2 complex for 8e.     

Combined effects of diamines and carboxylate bridges on structural and magnetic properties of a series of polynuclear copper(II) complexes with 1,1-cyclobutanedicarboxylic acid

Six new copper(II) complexes of formula [Cu(mu-cbdca)(H2O)]n (1) (cbdca = cyclobutanedicarboxylate), [Cu2(mu-cbdca)2(mu-bipy)2]n (2) (bipy = 4,4'-bipyridine), [Cu(mu-cbdca)(mu-bpe)]n (3) (bpe = 1,2-bis(4-pyridyl)ethane), [Cu(mu-cbdca)(bpy)]2 (4) (bpy = 2,2'-bipyridine), [Cu(terpy)(ClO4)]2(mu-cbdca).H2O (5) (terpy = 2,2':6',2' '-terpyridine), and [Cu(cbdca)(phen) (H2O)].2H2O (6) (phen = 1,10-phenanthroline) were obtained and structurally characterized by X-ray crystallography. Complex 1 is a two-dimensional network with a carboxylate bridging ligand in syn-anti (equatorial-equatorial) coordination mode. Complexes 2 and 3 are formed by chains through syn-anti (equatorial-apical) carboxylate bridges, linked to one another by the corresponding amine giving two-dimensional nets. Complexes 4 and 5 are dinuclear, with the copper ions linked by two oxo (from two different carboxylate) bridging ligands in 4 and with only one carboxylate showing the unusual bis-unidentate mode in complex 5. Complex 6 is mononuclear, with the carboxylate linked to copper(II) in a chelated form. Intermolecular hydrogen bonds and pi-pi stacking interactions build an extended two-dimensional network. Magnetic susceptibility measurements of complexes 1-5 in the temperature range 2-300 K show the occurrence of weak ferromagnetic coupling for 1 and 4 (J = 4.76 and 4.44 cm(-1), respectively) and very weak antiferromagnetic coupling for 2, 3, and 5 (J = -0.94, -0.67, and -1.61 cm(-1), respectively). Structural features and magnetic values are compared with those reported for the similar copper(II) malonate and phenylmalonate complexes.